Touch sensing technology capable of providing a natural interface between an electronic system and user has found widespread applications in a variety of fields, for example, in mobile phones, personal digital assistants (PDAs), automatic teller machines (ATMs), game machines, medical devices, liquid crystal display (LCD) devices, light emitting diode (LED) devices, plasma display panel (PDP) devices, computing devices, and the like, where a user may input desired information and/or operate the electronic system through a touch sensing device associated with the electronic system. A touch sensing device typically includes a controller, a sensing circuit having a plurality of touch sensors and a network of control lines electrically connecting the plurality of touch sensors to the controller, and a touch screen associated with the plurality of touch sensors.
There are at least two types of touch sensors available for detection of a touch location. One is a resistive touch sensor that includes two layers of transparent conductive material, such as a transparent conductive oxide, separated by a gap. When touched with sufficient force, one of the conductive layers flexes to make contact with the other conductive layer. The location of the contact point is detectable by a controller that senses the change in resistance at the contact point. In response, the controller performs a function, if any, associated with the contact point. The other is a capacitive touch sensor that typically includes a single conductive layer for touch detection. A finger touch to the sensor provides a capacitively coupled path from the conductive layer through the body to earth ground. The location of the contact point is detectable by a controller that measures a change in a capacitively coupled electrical signal at the touch location. Accordingly, the controller performs a function, if any, associated with the touch location.
FIG. 5 shows a typical layout of a plurality of touch sensors in a touch sensing device. The plurality of touch sensors {Si,j} are arranged in the form of a matrix having m rows and n columns, where i=1, 2, 3, . . . , m, and j=1, 2, 3, . . . , n. For the touch sensors {Si,J} of the J-th column, each is connected to one another in series by a control line, XJ, along the direction of the J-th column, where J=1, 3, 5, . . . (n−1) for n being an even integer, or J=1, 3, 5, . . . , n for n being an odd integer. For the touch sensors {Si,K} of the remaining columns, i.e., K=2, 4, 6, . . . n for n being an even integer, or J=2, 4, 6, . . . , n−1 for n being an odd integer, each of the touch sensors {Si,K} in the i-th row is connected to one another in series by a control line, Yi, along the direction of the i-th row, where i=1, 2, 3, . . . , m. The control lines XJ and Yi, in turn, are connected to a controller (not shown). Preferably, the control lines XJ and Yi are conductive wires and are separated by an insulator, as shown in FIG. 6.
For such a touch sensor layout, however, there are several drawbacks. First, at least [m+(n/2)] control lines for N being an even integer or [m+((n+1)/2)] control lines for n being an odd integer are needed to connect the (m×n) touch sensors {Si,j} to the controller in this sensor layout. For a touch sensing device having a large number of touch sensors, the sensor layout poses the great challenge and difficulty in manufacturing. Furthermore, the use of a large number of control lines may result in a great amount of impedances, thereby lapsing the response time and reducing the sensitivity of the sensing circuit. Second, the sensing resolution of the touch sensing device in the X (row) direction is different from that in the Y (column) direction.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.